1 , 3 , 6 , 10 , 15

1) What is the nth term of the sequence?

2) Use the nth term to work out the 21st term of the sequence.

Answers

Answer 1

First difference,

[tex]\Delta_{1} = a_{2} - a_{1} = 3 - 1 = 2 = 1 + 1[/tex]

Second difference,

[tex]\Delta_{2} = a_{3} - a_{2} = 6 - 3 = 3 = 2 + 1[/tex]

Third difference,

[tex]\Delta_{3} = a_{4} - a_{3} = 10 - 6 = 4 = 3 + 1[/tex]

And so on.

Assuming the pattern holds on, we see that

i-th difference,

[tex]\Delta_{i} = a_{i + 1} - a_{i} = i + 1[/tex]

[tex]\implies a_{i + 1} = a_{i} + i + 1[/tex]

Then, nth term is,

[tex]\implies a_{n} = a_{n - 1} + n[/tex]

[tex]= a_{n - 2}+ (n + (n - 1))[/tex]

[tex]= a_{n - 3} + (n + (n - 1) +(n - 2))[/tex]

[tex]= a_{n - (n - 1)} + \sum \limits^{n - 2}_{k = 0}(n - k)[/tex]

[tex]= a_1 + \sum \limits^{n - 2}_{k = 0}n- \sum \limits^{n - 2}_{k = 0}k[/tex]

[tex]= a_1 +n(n -2 + 1 )- \frac{1}{2} (n - 2)(n - 1)[/tex]

[tex]= a_1 +n(n -1 )- \frac{1}{2} (n - 2)(n - 1)[/tex]

[tex]= a_1 +(n -1 )(n- \frac{1}{2} (n - 2))[/tex]

[tex]= a_1 + \frac{1}{2} (n -1 )(2n- n + 2)[/tex]

[tex]= a_1 + \frac{1}{2} (n -1 )(n + 2)[/tex]

[tex]\implies a_{n} = 1 + \frac{1}{2} (n -1 )(n + 2)[/tex]

Now, the 21st term in the sequence is,

[tex]\implies a_{21} = 1 + \frac{1}{2} (21 -1 )(21 + 2)[/tex]

[tex]= 1 + \frac{1}{2} \times 20 \times 23[/tex]

[tex]= 231[/tex]


Related Questions

plz help...........​

Answers

Answer:

1 is one of them

Step-by-step explanation:

1 is one of them... tbh just try

$36 - $12.75 =
Pls answer

Answers

$36 - $12.75 is $23.25

Jesus is looking for a new gym Fitness Connection costs $6 to join with a monthly fee of $14. Fitness World costs $10 to join with a monthly of \$12 . Which oquation and solution represent the number of months will take for both gymo to cost the same?

Answers

jesus do be gettin buff doe

Answer the link at the bottom plz

Answers

Answer:

2/3

Step-by-step explanation:

24students - 8 boys = 16 girls

16/24

2/3

Answer:

[tex]\frac{16}{24}=\frac{2}{3}[/tex]

also

[tex]\frac{8}{24} =\frac{1}{3}[/tex]

Step-by-step explanation:

Write a multiplication fact that goes with this division fact.

33 ÷ 11 = 3

Answers

Answer: 3 x 11 = 33

Step-by-step explanation: Hope it helped!

what is the simplest form of this ratio?
100:40:20

Answers

Answer:

52

Step-by-step explanation:

y=x-1
y=x+1
((This is System of Equations))

Answers

Add 1 to both sides of the equation.

y = x - 1

2x = 3 + 1

Add 3 and 1 .

y = x - 1

2x = 4

The variables x an y vary directly. When x=13, y=52. Which equation correctly relates x and y?

Answers

Answer:

The equation which correctly relates x and y is y = 4x

Step-by-step explanation:

The equation of the direct variation is y = k x, where

k is the constant of variationTo find the value of k, use the initial values of x and y

∵ The variables x and y vary directly

→ Use the form of the equation above

y = k x

∵ When x = 13, y = 52

→ That means the initial values of x and y are 13 and 52

x = 13 and y = 52

→ Substitute them in the equation above to find k

52 = k (13)

∴ 52 = 13k

→ Divide both sides by 13

4 = k

∴ The value of k is 4

→ Substitute it in the equation

y = 4x

The equation which correctly relates x and y is y = 4x

Question 2 of 10
Is ABC - ALMN? If so, name which similarity postulate or theorem applies.
B
75°
75
50"
А
50"
C
N
A. Similar - AA
B. Similar - SSS
C. Similar - SAS
D. Cannot be determined

Answers

A

Step-by-step explanation:

two of the triangles' corresponding angles are the same even if the side lebgths are not, making these two similar

By AA similarity triangle ABC and triangle LMN are similar. Therefore, option A is the correct answer.

What are similar triangles?

Two triangles are similar if the angles are the same size or the corresponding sides are in the same ratio. Either of these conditions will prove two triangles are similar.

In the given triangle ABC, ∠A=50° and ∠B=75°.

In the given triangle LMN, ∠L=50° and ∠M=75°

From the given triangles,

∠A=∠L=50°

∠B=∠M=75°

By AA similarity triangle ABC and triangle LMN are similar.

Therefore, option A is the correct answer.

To learn more about the similar triangles visit:

https://brainly.com/question/25882965.

#SPJ5

Find the value of Angle A and B!!! Will mark brainliest

Answers

Answer:

A=73

B=107

Step-by-step explanation:

since the angles are across from eachother they would be the same, the total angle of all 4 added together would be 360, and 73+107 would be 180, so 180+180 is equal to 360

The function y - 3 = 4(x + 2) is in point-slope form. Select the equivalent equation in slope-intercept form
y = 112 +4
y = 4.3 +11
y = 4x + 5
y = 4x + 8

Answers

The answer is B. y=4x + 11

7x – 2y = -5 which is the correct answer help a homie out pls

Answers

Neither of those work for that equation

Suppose Metro by T-Mobile wants to offer a simple extended warranty plan. If your phone is damaged, they will repair it for up to $50. If you lose or destroy your phone, they will give you a $200 voucher towards a new phone. The company believes that 5% of customers will need the replacement voucher and 10% will request a repair. What is the standard deviation?

Answers

Answer:

45

Step-by-step explanation:

Given that :

Voucher awarded (x) :

Repair = $50

Lose or destroy = $200

P(x):

Replacement voucher = 5%

Repair voucher = 10%

X ______ 50 ______ 200

P(x) ____ 0.1 _______ 0.05

Expected variance Var(X) :

ΣX²p(x) - E(x) ;

E(x) = Σx*p(x) = (50*0.1) + (200*0.05) = 15

ΣX²p(x) = Σ[(50^2 * 0. 1) + (200^2 * 0.05)] = 250 + 2000 = 2250

Var(X) = 2250 - 15^2 = 2025

Standard deviation = √Var(x)

Standard deviation = √2025

Standard deviation = $45

Find the value of 3w-1 given that - 2w+8= 6.
Simplify your answer as much as possible.

Answers

Answer:

-4

Step-by-step explanation:

Given 2w + 8 = 6, find w

2w = -2w = -1

found w = -1, sub it into 3w - 1

3w - 1 = 3(-1) -1-3 - 1= -4

Which equation could be used to find the value of x in the triangle below? (pls help)

Answers

Answer:

B.

Step-by-step explanation:

All of it needs to add up to 180

So you have

2x + 4x+10 + 6x-10 = 180

Combine like terms

12x=180

B- 12x = 180 because all of the numbers need to equal to 180

what is the answer?​

Answers

Answer:

HL

Step-by-step explanation:

The hypotenuse and the "leg" are congruent...along with the 90 degree angle.

"The HL Postulate states that if the hypotenuse and leg of one right triangle are congruent to the hypotenuse and leg of another right triangle, then the two triangles are congruent." - Calcworkshop

The correct answer HL

What is the Slope of the line?

Answers

Answer:

1/2

Step-by-step explanation:

●••□■♤□●|□¤○|€♡■●~3}£₩9¥¥♡♡■{{6899

I need help finding a, b, and c. Thank you!

Answers

x^2 + 4x - 3 = 0
a b c

Answer:
a = 1
b = 4
c = -3

the radius of the base of a right cylinder is 12 cm and the height and the height of the cylinder is 18 cm. in terms of pi what is the volume of the cylinder.

Answers

Answer:

Step-by-step explanation:r=12cm,h=18cm,v=?

Vol. Of a cylinder=Πr²h

V= Π×12²×18

V= Π×144×18

V=2592Πcm³

What percent of 35 is 21

Answers

Answer:

7.35

Step-by-step explanation:

Answer:

60%

Step-by-step explanation:

Hope this helps!!!

Can I have Brainliest???

Choose the property of real number that justifies the equation. Last time I asked this the picture was cut out! Please answer quick I’m timed!

Answers

Answer:

I am thinking it is distributive property

Please help me answer this question thank you !!

Answers

Answer:

c

Step-by-step explanation:

3
42 ➗ (15-2)
I don’t know know to do this

Answers

Answer:

Step-by-step explanation:

42/13=4

If the ratio of ducklings to mama ducks is 7 to 1 how many ducklings would there be if there were 5 mama ducks? Use a table to solve using ratios!
Help me quickly

Answers

i believe you would do 5x7
for every one mom duck there’s 7 babies
so therefore if you had 5 momma ducks you would have 35 ducklings
hope this helps!

Answer:

There would be 35 ducklings

Step-by-step explanation:

If the ratio to baby ducklings to mama ducks is 7 to 1 then the constant of proportionality is 7. So you take the amount of mama ducks and multiply that by 7 you get your answer.

7 x 5 = 35

Put these in order starting from the smallest
62
34
25
59

Answers

Answer:

25 34 59 62

Step-by-step explanation:

easy shi thanks

25

34

59

62

Hope this helped

A car lot owner is trying to get rid of this year's inventory to make room for the new vehicles. He paid $25,599 for a red truck. If he sells it to a customer for $22,000, what mark down percentage did he use?

Answers

Answer:

14%

Step-by-step explanation:

Step one

given data

Cost price of vehicle=  $25,599

Selling price of vehicle= $22,000

Required

The percentage discount in the price

Step two:

% discount= cost price-selling price/cost price*100

% discount= 25,599-22,000/25,599*100

% discount= 3599/25,599*100

% discount= 0.140*100

% discount= 14%

The mark down percentage use is 14%

Which relation is a function? Group of answer choices (2, 7), (6, 5), (4, 4), (3, 3), (2, 1) (9, −3), (9, 3), (4, −2), (4, 2), (0, 0) (1, 0), (3, 0), (1, 1), (3, 1) (1, 3) (1, 1), (2, 2), (3, 3), (4, 4), (5, 8)

Answers

Given:

The relations in the options.

To find:

The relation which is a function.

Solution:

Consider the options are :

(a) {(2, 7), (6, 5), (4, 4), (3, 3), (2, 1)}

(b) {(9, −3), (9, 3), (4, −2), (4, 2), (0, 0)}

(c) {(1, 0), (3, 0), (1, 1), (3, 1) (1, 3)}

(d) {(1, 1), (2, 2), (3, 3), (4, 4), (5, 8)}

A relation is a function if there exist a unique y-value for each x-value.

In option (a), y=7 and y=1 at x=2. So, it is not a function.

In option (b), y=-3 and y=3 at x=9. So, it is not a function.

In option (c), y=0 and y=1 at x=3. So, it is not a function.

In option (d), there are unique y-value for each x-value. So, it is a function.

Therefore, the correct option is (d).

A contestant in a game show has​ 9,000 points. The contestant answers the next question incorrectly and loses 750 points. Does the word​ "lose" suggest a positive integer or a negative​ integer? What integer represents a loss of 750​ points?

Answers

This question is incomplete

Complete Question

A contestant in a game show has​ 9,000 points. The contestant answers the next question incorrectly and loses 750 points. Does the word​ "lose" suggest a positive integer or a negative​ integer? What integer represents a loss of 750​ points?

a) Positive, + 750

b) Positive , - 750

c) Negative , +750

d) Negative , - 750

Answer:

d) Negative , - 750

Step-by-step explanation:

We are told in the question that the contestant has 9000 points

Then he loses 750 points.

This means that the 750 points would be deducted from the 9000 points he the contestant has already.

The word lose is a negative and it carries the Subtraction (-) sign,

hence, lose suggests a negative integer which is given as:

-750

Option d is the correct option

Which expressions are equivalent to (5g+3h+4)•2?

Answers

Answer:

nc

Step-by-step explanation:

nc

What is the measure of <6
<6=

Answers

Answer:

20/20

Step-by-step explanation:

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